The AMS 4640 specification began in 1940 and was simply AMS 4640. The first revision was in 1945 when it became AMS 4640A. Every revision in the years after that just took the next letter in the alphabet. AMS 4640B in 1951, AMS 4640C in 1952, AMS 4640D in 1984, and so on. AMS 4640 is used extensively in landing gear bushings for aircrafts. This alloy also finds use in other industries such as oil and gas and engine components as well as many others.